Not too many, really. Only takes a couple of minutes to go through 18 holes and edit it on the computer. The things I usually have to edit:
—hit fairway or not (only an issue if your shot is close to where they’ve got the edge of the fairway mapped). I’m not sure you can edit this on the iPhone.
—position of putts and hole. You can edit this on the iPhone, but I find it hard to do on a little screen.
—Using putter off the green (Texas wedge). The iPhone app will move these onto the green and count them as putts. If I want to show these as not being putts, I have to edit it on the computer.
—provisional shots, lost ball, penalty strokes. You can edit these on the iPhone app. Sometimes I’ll just do it on the computer since I’m usually going to review the round anyway.
Edit: an easy way to demo how it works is to go online and create a user account (free) and download the smartphone app (android or iPhone, free). When you’re going to play a round where you won’t be rushed or anything, use the app to record your shots. It’s a nuisance to manually record each shot on the phone app, but at the end of the round you’ll have the data recorded and can see what it does with the info. (I went to a local executive course I know well and usually has a slow pace so I wouldn’t hold things up while I was messing with my phone.)